Multiple load path transmissions are frequently employed where spacial and weight constraints are of considerable concern. In the usual case, several nominally identical gear trains are placed in parallel so as to be independent of one another and carry the same load as one single gear train utilizing components that are of lesser size and of lesser weight. Through careful organization of the gear trains, the overall size of the transmission can be reduced over that utilizing a single load path as well.
Systems of this type may be advantageously employed for example, in aircraft or, for example, in naval torpedoes. One problem is almost universally attendant the use of multiple load path transmissions. Manufacturing errors or tolerances will frequently result in one of the paths in the transmission carrying a greater load than another leg or legs. If this situation is permitted to occur, each leg must be designed to carry somewhat more load than is necessary in order to compensate for the possibility of manufacturing errors. This, of course, means a loss of the advantages attendant multiple load path transmissions. Further, noise generation will increase because of the mismatch in load paths.
To avoid these difficulties, attempts have been made to provide some means in the paths of the multiple load path transmission to compensate for manufacturing errors. Not infrequently, a torsion shaft will be utilized and one end may twist relative to the other until load equalization throughout the transmission is obtained.
This solution, while mechanically satisfactory, increases the length of the transmission because of the need for a relatively long torsion shaft.
The assignee of the present application has proposed to eliminate this difficulty by utilizing, in each leg of a multiple load path transmission, a torsionally compliant gear wherein a gear tooth ring is carried by a hub and is connected thereto by a bonded layer of elastomer. This not only compensates for unequal loading by allowing adjustment within the system to achieve equal loading, it provides a measure of noise isolation of various parts of the transmission from others which is particularly advantageous in naval torpedoes operating in a so-called "search" mode. Because the sole connection between the ring and the hub is by means of elastomeric material, for a given sized gear, high level loading cannot be achieved as easily as desired.
The present invention is directed to overcoming one or more of the above problems.